This invention relates to a variable capacity wobble plate compressor for compressing refrigerant circulated within air conditioning systems for automotive vehicles, or the like.
Among conventional variable capacity wobble plate compressors of air conditioning systems for automotive vehicles, there is a type in which rotational speed sensor means detects a substantial difference between the rotational speed of an engine installed on the vehicle and the rotational speed of the compressor due to a defect in the compressor itself or in the clutch connecting between the compressor and the engine, and then the clutch becomes disengaged in response to a signal indicative of the detected speed difference to protect other auxiliary equipment driven by the engine via the same driving belt as the compressor.
According to this conventional compressor, the rotational speed sensor means is adapted to detect only the rotational speed of the compressor, but is not adapted to detect the angularity of the wobble plate. However, there is a demand for such rotational sensor means as is capable of detecting the angularity of the wobble plate as well as the rotational speed of the compressor, because such sensor means would prove to be useful in controlling the operation of the compressor. For example, if such dual-function sensor means is provided, it will be possible to compare the actual stroke amount of the pistons of the compressor with a desired preset value on the basis of signals from the sensor means indicative of detected compressor rotational speed and wobble plate angularity, and correct the piston stroke amount by the stroke amount difference so as to control the delivery quantity or capacity of the compressor to a desired value. Further, it will be also possible to check whether there is any abnormality in the compressor, on the basis of the signals from the sensor means.